8,456 research outputs found
Graffiti Networks: A Subversive, Internet-Scale File Sharing Model
The proliferation of peer-to-peer (P2P) file sharing protocols is due to
their efficient and scalable methods for data dissemination to numerous users.
But many of these networks have no provisions to provide users with long term
access to files after the initial interest has diminished, nor are they able to
guarantee protection for users from malicious clients that wish to implicate
them in incriminating activities. As such, users may turn to supplementary
measures for storing and transferring data in P2P systems. We present a new
file sharing paradigm, called a Graffiti Network, which allows peers to harness
the potentially unlimited storage of the Internet as a third-party
intermediary. Our key contributions in this paper are (1) an overview of a
distributed system based on this new threat model and (2) a measurement of its
viability through a one-year deployment study using a popular web-publishing
platform. The results of this experiment motivate a discussion about the
challenges of mitigating this type of file sharing in a hostile network
environment and how web site operators can protect their resources
Isospin breaking, coupled-channel effects, and X(3872)
We re-investigate the possibility of X(3872) as a molecule with
within the framework of both the one-pion-exchange (OPE) model
and the one-boson-exchange (OBE) model. After careful treatment of the S-D wave
mixing, the mass difference between the neutral and charged mesons and
the coupling of the pair to , a loosely bound molecular
state X(3872) emerges quite naturally with large isospin violation in its
flavor wave function. For example, the isovector component is 26.24% if the
binding energy is 0.30 MeV, where the isospin breaking effect is amplified by
the tiny binding energy. After taking into account the phase space difference
and assuming the and come from a virtual omega and rho meson
respectively, we obtain the ratio of these two hidden-charm decay modes:
for the binding
energy being 0.3 MeV, which is consistent with the experimental value.Comment: published in Phys. Rev.
A Framework for Life Cycle Sustainability Assessment of Road Salt Used in Winter Maintenance Operations
It is important to assess from a holistic perspective the sustainability of road salt widely used in winter road maintenance (WRM) operations. The importance becomes increasingly apparent in light of competing priorities faced by roadway agencies, the need for collaborative decision-making, and growing concerns over the risks that road salt poses for motor vehicles, transportation infrastructure, and the natural environment. This project introduces the concept of Life Cycle Sustainability Assessment (LCSA), which combines Life Cycle Costing, Environmental Life Cycle Assessment, and Social Life Cycle Assessment. The combination captures the features of three pillars in sustainability: economic development, environmental preservation, and social progress. With this framework, it is possible to enable more informed and balanced decisions by considering the entire life cycle of road salt and accounting for the indirect impacts of applying road salt for snow and ice control. This project proposes a LCSA framework of road salt, which examines the three branches of LCSA, their relationships in the integrated framework, and the complexities and caveats in the LCSA. While this framework is a first step in the right direction, we envision that it will be improved and enriched by continued research and may serve as a template for the LCSA of other WRM products, technologies, and practices
Deuteron-like states composed of two doubly charmed baryons
We present a systematic investigation of the possible molecular states
composed of a pair of doubly charmed baryons () or one doubly
charmed baryon and one doubly charmed antibaryon
within the framework of the one-boson-exchange-potential model. For the
spin-triplet systems, we take into account the mixing between the and
channels. For the baryon-baryon system with and , where and represent the group
representation and the isospin of the system, respectively, there exist loosely
bound molecular states. For the baryon-antibaryon system
with , and , there
also exist deuteron-like molecules. The molecular states
may be produced at LHC. The proximity of their masses to the threshold of two
doubly charmed baryons provides a clean clue to identify them.Comment: 18 pages, 8 figure
Possible hadronic molecules composed of the doubly charmed baryon and nucleon
We perform a systematical investigation of the possible deuteron-like bound
states with configuration , where denotes the
nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential
model. In the spin-triplet sector we take into account both the and
channels due to non-vanishing tensor force. There exist several
candidates of the loosely bound molecular states for the and
systems, which lie below the threshold of
or . We also investigate the
possible loosely bound states with configurations and
. These molecular candidates may be searched for at Belle
II and LHC in the near future.Comment: 14 pages, 5 figure
Localized Dimension Growth in Random Network Coding: A Convolutional Approach
We propose an efficient Adaptive Random Convolutional Network Coding (ARCNC)
algorithm to address the issue of field size in random network coding. ARCNC
operates as a convolutional code, with the coefficients of local encoding
kernels chosen randomly over a small finite field. The lengths of local
encoding kernels increase with time until the global encoding kernel matrices
at related sink nodes all have full rank. Instead of estimating the necessary
field size a priori, ARCNC operates in a small finite field. It adapts to
unknown network topologies without prior knowledge, by locally incrementing the
dimensionality of the convolutional code. Because convolutional codes of
different constraint lengths can coexist in different portions of the network,
reductions in decoding delay and memory overheads can be achieved with ARCNC.
We show through analysis that this method performs no worse than random linear
network codes in general networks, and can provide significant gains in terms
of average decoding delay in combination networks.Comment: 7 pages, 1 figure, submitted to IEEE ISIT 201
Chiral Perturbation Theory and the Strong Interaction
We have calculated the potentials of the heavy (charmed or bottomed)
pseudoscalar mesons up to with the heavy meson chiral
perturbation theory. We take into account the contributions from the football,
triangle, box, and crossed diagrams with the 2 exchange and one-loop
corrections to the contact terms. We notice that the total 2-exchange
potential alone is attractive in the small momentum region in the channel
, , or , while repulsive in the channel .
Hopefully the analytical chiral structures of the potentials may be useful in
the extrapolation of the heavy meson interaction from lattice QCD simulation.Comment: 14 pages, 8 figures, 4 tables; discussion extended, references added,
version published in Phys. Rev.
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